1. Field of the Invention
The present invention generally relates to subsea production facilities, and more particularly, to an insulation shroud with an internal support structure.
2. Description of the Related Art
There are thousands of subsea oil and gas wells, and associated production equipment, located throughout the world. Such subsea facilities include numerous pipe designs and connectors that are employed to connect various items of subsea equipment to one another. In many subsea hydrocarbon fields, a certain amount of water is produced along with the hydrocarbons. This is commonly known as the water cut. As fields approach the end of their productive lives, the water cut can exceed 50% or more of the produced fluid. Another contributor of water cut may be seawater that is injected to maintain reservoir pressure. This injected seawater can be produced back by the production wells. When the right combination of high pressure and low temperature is present, this mixture of produced hydrocarbons and produced water has the potential to form solid hydrates, which can form blockages in the production system. This is a common problem in deepwater wells, because of the high hydrostatic pressure and the low temperature of the surrounding seawater.
In normal operation, the produced fluid flows through the production equipment at a temperature well above the hydrate formation temperature. As the fluid continues to flow to a surface facility, it does not have time to cool, and thus hydrate formation is not an issue. However, situations can occur which require a planned or unplanned shutdown of the production system for extended periods of time. When this occurs, the produced fluid that remains trapped in the production equipment located above the floor of the ocean is cooled by the surrounding seawater. If this trapped fluid remains static for too long, it will cool below the hydrate formation temperature and solid hydrates may form. Avoiding hydrates and wax blockages is an important aspect of subsea systems flow assurance management, system reliability, and safety of subsea production systems. The subsea industry has increased focus on flow management issues significantly due to the more challenging environments encountered in deepwater fields and the high cost of remediation.
One technique that is employed in an effort to prevent or reduce hydrate formation is to provide insulation around the components to delay the cooling of the hydrocarbon fluid. FIG. 1 depicts an illustrative embodiment of a prior art insulating shroud 10 employed with subsea connectors 12 to prevent or reduce hydrate formation. The prior art insulating shroud 10 comprises insulation material 14, a seal 16, and an outer plastic shell 18. The shroud 10 further comprises a hinged door 20 with latches 17 that is adapted to be closed after the shroud 10 is positioned around the subsea connector 12. The outer plastic shell 18 is designed to, among other things, provide rigidity to the insulation 14. The insulation 14 must be rigid enough such that it does not distort under its own weight, and thereby allows the shroud 10 to seal against the connector 12 when it is installed for it to serve its insulating function.
While the prior art design depicted in FIG. 1 has proven to be acceptable, there are problems associated with the use of such a design. First, given the techniques employed in making the outer plastic shell 18, it is difficult to obtain shells 18 with sufficient dimensional accuracy. Additionally, the tooling used to make the prior art outer plastic shells 18 is relatively expensive and does not readily allow the profile of the outer plastic shell 18 to be changed as system requirements change.
The present invention is directed to various devices and methods for solving, or at least reducing the effects of, some or all of the aforementioned problems.